Amazing thread; have been looking for something with that data for a long time now. I still see a 10% difference. I would not choose the 6MT if I knew it was an afterthought for the car and crippled the vehicle's performance. 10% is a fine penalty for me since 99% of the driving fun I derive from the M3 is spent lazily rowing through the gears enjoying the responsiveness of the car. Plus in real world conditions to 60mph the manual is apparently a tiny bit faster to 60mph than the DCT, considering that the 1-2 shift is nearly instantaneous on the 6MT at redline and MDM provides an excellent and consistent launch.

High rpm strung engine, more flexible, pure driving excitement at all times = S65 . e92 / FEI - there is plenty of torque available in the
S65 engine, just have to drive the car like it is meant to be driven...

If you really like driving you would enjoy both with its own characteristics.

CURRENT RIDES
12 FROZEN SILVER E92 M3
03 GP WHITE S2K AP1

ORDERED
13 MONTECARLO BLUE F10 M5

PREVIOUS M CARS
02 LEMANS BLUE E39 M5
06 SAPPHIRE BLACK E60 M5

Nice car collection. You must be a BMW fan. This is my first BMW and first nice car. I'm keeping it

Not totally correct, since power is in linear direct proportionality to torque, torque is very important, you just need to know rpm and gearing to get the entire picture.

You don't need to know anything about torque and gearing. Just power.

Quote:

Originally Posted by MKE_M3

Correct, but generally peak power is fairly close to redline, which I assume Munit meant.

And I assume Munit meant what he typed. Maybe he'll illuminate us.

Quote:

Originally Posted by MKE_M3

I think you are forgetting about the third component to acceleration, traction. Not too much an engine design can do here, but linear power delivery certainly helps. Something both engines have.

I also "forgot" about air resistance, rolling resistance, driveline friction and rotational inertia. My central point is that power and weight govern acceleration at any given speed, while torque and gearing needn't be considered. You can also predict acceleration by doing the torque-at-the-drive-wheels calculations, but why bother?

Bruce

PS - What in God's name is linear power delivery, and how does it help with traction.

To get how much power the car is putting down, you need torque and gearing. That is science.

Rather than get into a long discussion with you on what, after all, is a very basic point about power, let me first mention that you cannot multiply power through gearing. Only torque. A seventh grade science book will tell you that.

Obviously car two will need to be in a different gear so as to be at 4150 rpm, or for this example, the final drive will have to be half the stock final drive ratio, numerically speaking.

Car three needs a quarter (numerically speaking) final drive.

OK, so these three cars are cruising side-by-side at around 100 MPH. The stocker is capable of about 262 pound feet of torque at that point (per the formula), car two has to be making double that, and car three needs 1048 pound feet, again per the formula. Other than engines and gearing, the cars are identical, weigh the same, have similar rotational inertia at that point, blah blah blah.

So everybody floors it, and what happens at that instant?

The cars stay dead even is what happens. Granted, the stocker has to shift a split second later, but that's not important here.

What IS important is that, with wildly different gearing, wildly different engine speeds, and wildly different torque production, the cars accelerate identically at that point.

They do this because thay are making the same horsepower, and horsepower is the great shorthand in this context.

As I've mentioned, you can mess about with torque at the drive wheels (and I did for years), but there's no need. Horsepower is the great simplifier.

Quote:

Originally Posted by MKE_M3

Seriously?

Yes. Let me ask again: What in God's name is linear power delivery, and how does it help with traction.

Rather than get into a long discussion with you on what, after all, is a very basic point about power, let me first mention that you cannot multiply power through gearing. Only torque. A seventh grade science book will tell you that.

Obviously car two will need to be in a different gear so as to be at 4150 rpm, or for this example, the final drive will have to be half the stock final drive ratio, numerically speaking.

Car three needs a quarter (numerically speaking) final drive.

OK, so these three cars are cruising side-by-side at around 100 MPH. The stocker is capable of about 262 pound feet of torque at that point (per the formula), car two has to be making double that, and car three needs 1048 pound feet, again per the formula. Other than engines and gearing, the cars are identical, weigh the same, have similar rotational inertia at that point, blah blah blah.

So everybody floors it, and what happens at that instant?

The cars stay dead even is what happens. Granted, the stocker has to shift a split second later, but that's not important here.

What IS important is that, with wildly different gearing, wildly different engine speeds, and wildly different torque production, the cars accelerate identically at that point.

They do this because thay are making the same horsepower, and horsepower is the great shorthand in this context.

As I've mentioned, you can mess about with torque at the drive wheels (and I did for years), but there's no need. Horsepower is the great simplifier.

Yes. Let me ask again: What in God's name is linear power delivery, and how does it help with traction.

Bruce

Your example is confusing because an engine producing more torque at a lower RPM, that could continue to make that torque across a wide rpm range, will have a higher horsepower rating.

You are right in that horsepower IS the shorthand that generally summs up an engine's performance, but you can't just throw out gearing like it doesn't matter. The truth is, if the analogy is understood, we would also have to concede that in order for those engines to produce that torque at those rpm's and have that HP rating, they would all have to essentially shift very very soon.

Why does gearing still matter? Gearing still matters because given the same exact car (6MT M3 vs DCT M3), you can have one car consistently win. Let's take for a moment that the 6MT was being driven by a machine that could reproduce accurate shifts every single time, with zero time between shifts. It would still lose to the DCT car due to the gearing and how the torque curve is then translated to the road. Any advantage in to the wheel torque of the shorter 6MT first gear is negated by the available traction, and then it's all on the DCT's favor.

There is no way in hell an S62 is nearly 100 lbs lighter than an s65. They are both aluminum V8s with roughly the same size block. Just throwing that out there.

One could build a bored/stroked 7000 RPM S65 with 400 hp, but that would be seen as a big waste of money and a step backward by most. Similarly one could build a destroked 8400 RPM S62 with 414 hp but that would be seen as a waste of resources as well.

For racing applications, either engine is capable of 600hp+ once you equalize displacement and RPM. The S62 may have a higher deck (not sure) which would mean more displacement potential in theory. Both have an 98mm bore center like all BMW V8s. For a race series that does not allow altering the short block from stock, the S62 obviously has the advantage.

__________________

A gen-u-ine BMW eff-eight-zero with them tandem clutches in the transmission and that dad gum sun roof on the top-a da cawr.

There is no way in hell an S62 is nearly 100 lbs lighter than an s65. They are both aluminum V8s with roughly the same size block. Just putting that out there.

One could build a bored/stroked 7000 RPM S65 with 400 hp, but that would be seen as a big waste of money and a step backward by most. Similarly one could build a destroked 8400 RPM S62 with 414 hp but that would be seen as a waste of resources as well.

For racing applications, either engine is capable of 600hp+ once you equalize displacement and RPM. The S62 may have a higher deck (not sure) which would mean more displacement potential in theory. Both have an 98mm bore center like all BMW V8s. For a race series that does not allow altering the short block from stock, the S62 obviously has the advantage.

__________________

A gen-u-ine BMW eff-eight-zero with them tandem clutches in the transmission and that dad gum sun roof on the top-a da cawr.

There is no way in hell an S62 is nearly 100 lbs lighter than an s65. They are both aluminum V8s with roughly the same size block. Just throwing that out there.

One could build a bored/stroked 7000 RPM S65 with 400 hp, but that would be seen as a big waste of money and a step backward by most. Similarly one could build a destroked 8400 RPM S62 with 414 hp but that would be seen as a waste of resources as well.

For racing applications, either engine is capable of 600hp+ once you equalize displacement and RPM. The S62 may have a higher deck (not sure) which would mean more displacement potential in theory. Both have an 98mm bore center like all BMW V8s. For a race series that does not allow altering the short block from stock, the S62 obviously has the advantage.

That too seems suspect. Does the S62 use iron sleeves? I think it uses a spray on bore liner just like the S65. And the deck heights should be within 10mm. Aside from that difference, every other part in the engines should be within a couple percent weight-wise one way or the other. And both engine will have almost the same parts since they are both DOHC V8s with chain drive valvetrain and dual VANOS.

Yes. Let me ask again: What in God's name is linear power delivery, and how does it help with traction.

Bruce

I have a turbo E36M3. In 4th gear on a Dynojet in SAE, it makes 170 lbs rwtq and 80 rwhp at 2500 rpm, 517 lbs and 400 rwhp at 4000 rpm, 440 lbs and 500 rwhp at 6000 rpm, and 360 lbs and 480 rwhp at the 7200 rpm redline. The tires are 255/40/17. I find that in 2nd and 3rd gears, where the torque multiplication is higher, the torque comes in so hard and fast that I often lose traction and that once I lose traction, I do not regain it (maybe because the car is going sideways and I back off. From 3300 to 4000, it gains about 225 lbs rwtq, and this is usually the window in which the traction disappears. I have often wondered whether a more gradual power torque delivery would help with traction, and have considered the idea of running a bigger turbo to shift power higher while also increasing top end power and torque. I view more "linear" as more "gradual."

Your example is confusing because an engine producing more torque at a lower RPM, that could continue to make that torque across a wide rpm range, will have a higher horsepower rating.

Not to be a dick about it, but so what? If it makes it less confusing, let me postulate that the 4150 rpm engine has a red line of 4200, and the 2075 engine redlines at 2100. In addition, each engine is at its power peak, and they all have the same shape power and torque curves. It makes absolutely no difference, however, because I was specifically talking about what happens at the instant those three cars floor it, and not what happens at any other instant.

Quote:

Originally Posted by e1000

You are right in that horsepower IS the shorthand that generally summs up an engine's performance, but you can't just throw out gearing like it doesn't matter. The truth is, if the analogy is understood, we would also have to concede that in order for those engines to produce that torque at those rpm's and have that HP rating, they would all have to essentially shift very very soon.

Again, so what.

And while we're at it, I wasn't talking about how peak power more or less sums up an engine's performance. I was specifically pointing out that, at any given speed, horsepower and weight dictates how a car will accelerate at that instant, and torque, gearing and rpm are completely immaterial. Those three examples demonstrate the point vey adequately.

Quote:

Originally Posted by e1000

Why does gearing still matter? Gearing still matters because given the same exact car (6MT M3 vs DCT M3), you can have one car consistently win. Let's take for a moment that the 6MT was being driven by a machine that could reproduce accurate shifts every single time, with zero time between shifts. It would still lose to the DCT car due to the gearing and how the torque curve is then translated to the road. Any advantage in to the wheel torque of the shorter 6MT first gear is negated by the available traction, and then it's all on the DCT's favor.

Of course gearing matters across an engine's operating range - but again, my examples illustrate how power and weight are what dictate acceleration at any given instant, and for the umpteenth time, torque, gearing and rpm are immaterial in that context.

In your example of auto vs stick M3s in a drag race, let me suggest that both cars are at a sprayed drag strip, with track temps at, say, 90 degrees or so. I'm suggesting that to get away from what I consider is beside the point in this general discussion, and stick to the main points, which are gearing and shift speeds - not traction.

In that context, I'm thinking the stick car will have a minor advantage over a quarter mile (assumimg optimum launches for each vehicle), because it will launch harder, and will spend more time under power during the run because of the zero-length shifts.

No biggie. Just an observation.

Bruce

PS - In general, gearing tends to be a little less important than folks think in terms of acceleration. If you change the M3's final drive from a 3.85 ratio to, say, a 4.11, the car will clearly be able to put more torque to the drive wheels at any given engine speed, but that torque will be delivered at a lower vehicle speed.

The net effect is that the geared car will have the early advantage off the line, but when it shifts to second gear, the stocker will now have an advantage because it's still in first, and is now making more power (and of course more torque to the drive wheels) than the geared car. Then it has to shift and the geared car now has the edge...and so on.

Because the geared car has the early advantage in each gear, there are ET implications, given perfect traction, but trap speeds won't change much, because average power over the quarter mile won't change much, and it's power and weight that tend to govern trap speeds.

I have a turbo E36M3. In 4th gear on a Dynojet in SAE, it makes 170 lbs rwtq and 80 rwhp at 2500 rpm, 517 lbs and 400 rwhp at 4000 rpm, 440 lbs and 500 rwhp at 6000 rpm, and 360 lbs and 480 rwhp at the 7200 rpm redline. The tires are 255/40/17. I find that in 2nd and 3rd gears, where the torque multiplication is higher, the torque comes in so hard and fast that I often lose traction and that once I lose traction, I do not regain it (maybe because the car is going sideways and I back off. From 3300 to 4000, it gains about 225 lbs rwtq, and this is usually the window in which the traction disappears. I have often wondered whether a more gradual power torque delivery would help with traction, and have considered the idea of running a bigger turbo to shift power higher while also increasing top end power and torque. I view more "linear" as more "gradual."

Bad ass vehicle.

In my opinion, the tires are screaming (literally) for mercy because they are getting a stupendous amount of torque thrown at them, and the fact that the torque curve ramps up so quickly is not an issue.

As an aside, street tires (even sticky ones) tend to "go away" pretty rapidly once they pass around a 10% slip rate - which is the point where they show best traction, by the way. At a thirty or forty percent slip rate, it's starting to feel as if you're driving on ice.

Slicks don't peak, traction-wise, until they're slipping in the thirty to forty percent slip range, and fall off the traction curve way less rapidly.

There is no way in hell an S62 is nearly 100 lbs lighter than an s65. They are both aluminum V8s with roughly the same size block. Just putting that out there......The S62 may have a higher deck (not sure) which would mean more displacement potential in theory. Both have an 98mm bore center like all BMW V8s. For a race series that does not allow altering the short block from stock, the S62 obviously has the advantage.

Quote:

Originally Posted by mkoesel

That too seems suspect. Does the S62 use iron sleeves? I think it uses a spray on bore liner just like the S65. And the deck heights should be within 10mm. Aside from that difference, every other part in the engines should be within a couple percent weight-wise one way or the other. And both engine will have almost the same parts since they are both DOHC V8s with chain drive valvetrain and dual VANOS.

More info on S62:

"The S62 uses weight-saving silicon-impregnated cylinder walls and has a specific casting with 94.0-mm cylinders. The stroke is mm to 89.0 mm. This results in a displacement of 4941 cc, or approximately 5 liters. "Above all, we wanted to create an abundant torque curve," says BMW M engineer Wolfgang Kreinhfner modestly - and if that is the goal, to paraphrase what the hot-rodders used to say, "there's no substitute for liters." The cylinder centers are 98.0 mm apart, leaving only 4 mm of block surface between cylinders. For effective sealing with this tight cylinder spacing, BMW M engineers developed new 3-layer steel head gaskets."

Why S85 (E60 M5 engine) is not discussed here? Yes it is a V10 but the same displacement as the E39 M5 engine (5L). It does fit into the e92 M3 engine as well. the S65 is very similar to S85 with 2 missing cylinders. I would prefer S85 over S65 in my M3 any day. ~25% higher hp and torque.

I know it's more or less normal for folks on the Internet to accuse others of lying, as long as they're safely behind the keyboard, in Washington DC or elsewhere.

However, I genuinely want to know what MKE_M3 meant, and since's he's been present in the string, he can answer with more than single-word sarcasm.

I'm accusing you of feigning ignorance of one of the most repeated characteristics of this car in order to be in the position to provide a lesson. Please don't take offense.

I'll play. Everyone (sans yourself) talks about the "linear power delivery" of the M3. This exact phrase used by BMW themselves in their press release for the M3 CRT: "the high-revving unit provides the linear power delivery you expect from an M car." It is easy to control the amount of power to the wheels because the engine responds linearly to throttle response. A little bit of throttle, a little bit of power. A lot of throttle, a lot of power. Yet seemingly the ratio is constant; there seems to be a 1:1 ratio between your foot and how fast the car accelerates.

This is different to a car with a large peak throughout its rev range. No power, no power, no power, POWER!!! The sudden inconsistency of power application to the wheels from one moment to the other overloads available traction and the car becomes difficult to control.

The E9X is extremely easy to drive around town and in inclement weather due to this behavior. In fact to some it feels deceptively underpowered and underwhelming during test drives for this reason.

Or another way: If you smoothly and linearly accelerate, you don't spin the tires. If you smoothly accelerate and then stomp the accelerator (non-linear), you spin the tires. Isn't this obvious?

I enjoy reading your posts and find them educational. I hope you're not insulted that I think you're being purposely disingenuous -- I find it hard to believe you're not. I am hoping you will now translate my attempt into whatever the proper technical explanation may be.

For effective sealing with this tight cylinder spacing, BMW M engineers developed new 3-layer steel head gaskets."

Thanks for posting this information. I read that as well in my effort to confirm the S62 does not use press-in sleeves.

I assume you were bolding the part about the gaskets in an effort to suggest it can help account for the alleged weight difference? I am skeptical of that to say the least. I would need to see the shipping weight on those vs. the M3 head gaskets to be convinced. I highly doubt there is more than a pound or so difference between the two.

What are M3 gaskets made of, I wonder? There's only 6mm between cylinders in the S65. I suppose that is 50% more than an S62, but then we are also talking about a significantly higher compression ratio too.

__________________

A gen-u-ine BMW eff-eight-zero with them tandem clutches in the transmission and that dad gum sun roof on the top-a da cawr.

Those all seem on the 'light' side. Not sure what they are including in this weight. It is well documented even on BMWUSA website that the S65 weight is 202 kg (445 lb) like I mentioned in my previous post. In browsing online I found weights for the S85 and S62 in a comparison that CAR magazine did.